Abstract: A rail grinding unit comprises a support frame having opposite ends, an undercarriage having flanged wheels supporting each support frame end on the rails for mobility along a railroad track, a vertically adjustable carrier frame mounted on the support frame, an endless grinding band mounted on the carrier frame and trained about guide rollers under tension for rotation thereabout, a lower one of the guide rollers constituting a pressure roll for pressing the endless grinding band into grinding contact with the surface, and a vertical adjustment device connected to at least one of the frames for adjusting the depth of the grinding contact of the endless grinding band with the pressure roll in relation to the surface, the vertical adjustment device including a remote-controlled drive for operating the vertical adjustment device.

Abstract: A mobile apparatus for sequentially exchanging selected consecutive groups of old ties in an existing railroad track for groups of new ties while retaining groups of old ties therebetween to support the mobile apparatus on the track, comprises at least one bridge-like work vehicle having a frame defining an upwardly recessed portion between respective ends thereof, swivel trucks supporting the work vehicle frame ends on the railroad track, and a drive for the continuous advancement of the work vehicle on the railroad track in an operating direction. A succession of different individual devices are longitudinally displaceably mounted in the recessed frame portion of a respective work vehicle and are operative to effectuate different sequential operations for exchanging the selected old ties for the new ties, the tie exchanging devices including at least one tie pulling and inserting device.

Abstract: A mobile apparatus for sequentially exchanging selected consecutive groups of old ties in an existing railroad track for groups of new ties while retaining groups of old ties therebetween to support the mobile apparatus on the track, which comprises a continuously advancing bridge-like work vehicle having a machine frame defining an upwardly recessed portion between respective ends thereof and a respective swivel truck supporting each machine frame end. A continuous guide track is mounted atop the work vehicle and a power-driven tie transporting crane is mounted for mobility on the guide track.